Toshiba CF35E50, Technical Training Manual

Page: 84 / 139

84
To restart TV set, repair failure first.
8. KINK CORRECTION CIRCUIT
1. Outline
In the N5SS chassis, a kink correction circuit is employed to
correct a kink generating when receiving a black and white
pattern.
In the black and white pattern cross hatch shown in Fig. 11-
20, when the picture changes from black to white during field
scan period, a current Is flows rapidly in secondary of the
FBT and a current IP flows in reverse direction during scan
period (due to transformer coupling) in the primary winding.
This current works to increase the voltage across S character
correction capacitor CS. As a result, the deflection current
decreases by I1 as shown in Fig. 11-21 and the raster moves
toward left, thus causing the kink as shown in Fig. 11-22. On
the contrary, when the picture changes from black to white,
the reverse operation will occur.
2. Circuit Description
To correct the kink damping circuit is added between the
main B power line and the S character capacitor as shown in
Fig. 11-23.
In Fig. 11-24, a capacitor C441 is charged with a DC current
iB through Q442 connected to MAIN B during the flyback
period. When the voltage across C441 and S character
correction capacitor increases during the scan period, the
diode D442 conducts and reduces the voltage across C442 to
the original voltage level, thereby suppressing shift of the
raster.
Fig. 11-24
Fig. 11-20
Fig. 11-23
Fig. 11-21
Fig. 11-22
Cs
+
-
lp
ls
FBT
l1
Kink in the cross bar
pattern
Q404
C444 C440 L642
C442
C441
D442 R442
T461
C448 SIDE DPC
L461
C464
C467
D461
Kink Correction
Circuit
L462
Vcs
Vcs
C442
C441
D442
R442
MAIN
B
T461
C448
iB